Heavily armed radicals known as the Islamic State of Iraq and Al-Sham, or ISIS -- many of whom harvested their hate in Syria -- paraded through the northern Iraqi city of Mosul on Thursday, the latest city to be toppled on a tour of terror that's headed to Baghdad.

Top American officials are considering whether the U.S. should get involved again -- a tough call after the War in Iraq that spanned nearly nine years. In that time, nearly 5,000 Americans were killed, about 32,000 were injured and more than 1 million servicemen and women were deployed, with some having served several tours of duty. The cost of the war was estimated at $1.7 trillion.

Some vets in Maryland worry about the U.S. being pulled back into the conflict, but many felt that the U.S. shouldn't.

For many, if not all of those who served in the Iraq War, the latest news is a huge disappointment given all of the hard work they put in and the lives lost. Vets said it's painful to see fighters from the Al-Qaeda based ISIS group capture two key cities as they vow to take their fight to Baghdad.

Some of the vets WBAL-TV 11 News spoke to said they always thought this day might come.

"We did so much over there and came back. It was a fear of mine that things would revert to the way they were, and now, in fact, they have,” retired Marine Sgt. Jacob West said.

West did two tours in Iraq. He told 11 News it angers him to see the unrest in Iraq considering how much he and his fellow military members sacrificed over there.

"It's very disheartening because a lot of good men and women died while in Iraq, and in my opinion, it's absolutely ridiculous that, here we are, just a few years later after having withdrawn from Iraq, and the country is completely falling apart again," West said.

For current military members like Sgt. Major Thomas Beynard, of the Maryland Army National Guard, the attacks come as a shock.

"From December 2011 until August when we left Kuwait, we had relatively peaceful times," said Beynard, who also did two tours in Iraq.

Beynard was one of the last soldiers to leave. His unit helped provide areal security after the war.

"One of the reasons they kept us in Kuwait as part of our mission was to be able to respond had events like this occurred while we were still there," Beynard said.

As far as whether the U.S. should go back again, Beynard didn't comment, but West said the U.S. should not get involved.

"They told us that they wanted us gone and that they would take responsibility for their own country, and I think that's what they need to do," West said.

11 News also received a number of responses via social media from retired Iraq War vets echoing what West was saying: That the U.S. should have a limited to no role at all in the new conflict.

"When everyone left in 2011, it created this vacuum that some of these extremist groups are now beginning to fill," said Johns Hopkins University political science and international relations professor Steven David.

He said the situation puts President Barack Obama in a political pickle because he campaigned on ending the Iraq War.

"On the one hand, he certainly doesn't want to reintroduce American troops in large numbers back into Iraq. He doesn't want that -- virtually no one wants that. But on the other hand, he does not want to see the collapse of Iraq and the spreading of Islamic insurgency throughout the Middle East," David said.

Sen. John McCain is calling on the president's national security team to resign over not keeping Iraq secure.